Of our current energy/resolution paradigms
We know that ~20% of the universe is Dark Matter and that ~75% is Dark Energy. All we really know about Dark Matter is that it falls down and doesn't really interact with itself or anything else, really.
Dark Energy? Yeah, whatever it is, it pushes galaxies apart, that's about all we got.
There are a LOT of pretty easy discoveries to be made yet, but we just don't have the engineering to make them yet. The LHC was a marvel of engineering, but it can't even come close to the energy required to produce (theorized) Dark Matter particles. If you tried to make a bigger one, you'd need an LHC with a radius larger than the Earth's. That's not going to happen anytime soon, not by a long shot. We need another method than particle colliders, probably a very large space-based telescope to stare at black-holes with jets.
Biology is also rife with 'easy' things to do, but ones that we just don't have the tech for yet. Strangely, with all of the data that the Googs and the Zuck have, we have not seen a similar paradigm shift in psychology, criminology, or economics. At least in public literature.